The invention relates to a transformer having a plastics coil former with hollow winding tube. Wound between coil flanges of the plastics coil former are windings of different potentials. The flanges are provided with spacers to maintain the windings axially spaced from the flanges. An insulating layer, which extends from flange to flange, is interposed between the windings.
Particularly in the case of a conventional transformer in which a large potential difference between primary and secondary windings exists, transformer insulation requirements must be carefully observed. Suitable and well known techniques in complying with these requirements include the steps of insulating the windings from one another and proper dimensioning of air gaps and/or creepage paths (see for example EP-B-0,092,870).
The position of the transformer windings relative to each other are dictated by the required clearances between windings and must be maintained throughout the manufacturing process and service life of the transformer. In positioning the transformer windings within a conventional transformer, insulating parts, such as, for example, corrugated spacer rings, are disposed in the clearances between the windings. Production and mounting of these insulating parts in smaller transformers can be relatively expensive, significantly increasing the manufacturing cost.